ipr: Clear interrupt on croc/crocodile when running with LSI

commit 54e430bb upstream.

If we fall back to using LSI on the Croc or Crocodile chip we need to
clear the interrupt so we don't hang the system.

Tested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>